There are a number of different factors involved and it can all depend on the size of the 9.3.3 environment and what the proposed 11 environment is going to be.
As John mentioned there are number factors to take into consideration on the time it took for consideration.
also below mwntioed are some of the things to take into consdeartion before upgrade.
Before upgrading make sure all the clients installed in the environment are uninstalled and then carry on with the upgrade.
run the uninstall.cmd and remove all the clients installed on all servers.
like EAS console, Essbase client, EssbaseStudio, Excel addin, Financial Management client, FR Studio
Uninstaller location - <MIDDLEWARE_HOME>\EPMSystem11R1\uninstall\unistall.cmd/sh
Note - Please uninstall only the clients for Hyperion mentioned above.
Also if you have financial reporting studio , as it has been merged with 220.127.116.11 so it has to be removed and it will also
remove the windows service and the HR printers..
Take the backup of the business rules and LRO's before upgrading to 18.104.22.168
To take backup of LRO's run the below MaxL:-
export database sample.basic lro to server directory 'exportedLROs';
alter database sample.basic delete LRO all;
For Business Rules backup - go to EAS Console - Go to Business Rules - Right click on Business Rules and Click Export Business
Rules and make sure to select Calc Mgr and then keep the export.
After this start the process for Upgrade and its as usual normal installation folder.